In recent years, electrical components are mounted within a circuit board in order to improve electrical characteristics, including integration degree, smaller size packaging and lower noise affection. After electrical components are mounted in a circuit board, wiring layers (conductive layers) are layered thereon by a build-up method to form a multi-layered circuit board assembly. The electrical components and wiring layers are resin-molded.
However, according to a conventional multi-layered circuit board, heat generated from electrical components is hardly radiated and dissipated out of the assembly. As a result, a heat resistance is increased and power consumption is increased as well. Further, the assembly may be deformed due to such an undesired heat, and as a result, a reliability of the product is decreased.